The purpose of the current study was to determine if ultrasound is a useful tool to measure the venous characteristics of the lower extremity during a standard venous collecting cuff deflation protocol. To accomplish this, lower extremity pressure-cross sectional area (P-CSA) and pressure-volume (P-V) relationships were measured in 8 (25 ± 1 yr) supine subjects. Popliteal vein CSA was assessed using high resolution ultrasound while calf volume changes were simultaneously assessed using venous occlusion plethysmography (VOP). P-CSA and P-V relationships were assessed at baseline, during the cold pressor test (CP), and following sublingual nitroglycerin administration (NTG). Relationships were modeled with a quadratic regression equation and ₁ and ₂ were used as indices of venous compliance. Popliteal vein regression parameters ₁ (8.485 ± 2.616 vs. 7.638 ± 2.664, baseline vs. CP; 8.485 ± 2.616 vs. 7.734 ± 3.076, baseline vs. NTG; both P > 0.05) and 2 (-0.0841 ± 0.0241 vs. -0.0793 ± 0.0242, baseline vs. CP; -0.0841 ± 0.0241 vs. -0.0771 ± 0.0280, baseline vs. NTG; both P > 0.05) were not affected by CP or NTG. Similarly, calf regression parameters ₁ and ₂, obtained with VOP, were not altered during either trial. Intra-class correlations for venous compliance assessed with ultrasound and VOP were 0.92 and 0.97, respectively, indicating acceptable reproducibility. These data suggest that ultrasound is a functional and reproducible tool to assess the venous characteristics of the lower extremity, in addition to VOP. Additionally, popliteal vein and calf compliance were not affected by the CP test or NTG.